1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a device and method for driving a liquid crystal display device, which is capable of improving image quality and reducing power consumption by varying a light emission region of a backlight unit according to brightness characteristics of a display image.
2. Discussion of the Related Art
With increasing adoption of information technology, demands for an image display device have been variously increased. Recently, a flat panel display device such as a Liquid Crystal Display (LCD) device, a Field Emission Display (FED) device, a Plasma Display Panel (PDP) device, or a Light Emitting Diode (LED) display device is mainly used.
An LCD device displays a desired image by adjusting transmission amount of light supplied from a backlight unit by a liquid crystal panel including a plurality of liquid crystal cells arranged in a matrix.
In the related art, fluorescent lamps have been used as the primary light sources for backlight units. However, recently, with increasing miniaturization, thinness and weight reduction of backlight units, a backlight unit using LEDs, which are advantageous in terms of power consumption, weight and luminance, as compared to fluorescent lamps, has been used.
Such a backlight unit adjusts the amount of driving current supplied to light sources such as LEDs so as to control the brightness of a backlight. In the related art, a constant brightness may be supplied to a liquid crystal display device regardless of an image displayed on the liquid crystal display device.
In the backlight of the related art, a plurality of LEDs is connected in series or in parallel so as to form a plurality of LED groups, and driving current is supplied to the LED groups so as to control the overall brightness of the backlight. However, since the plurality of LED groups generates a constant brightness or the brightnesses of the plurality of LED groups are equally varied, power consumption may be increased. For example, even when the brightness of the display image is high or low in a portion of the screen, all the LED groups generate the same amount of light in both a dark region and a bright region. Thus, power consumption is increased. In addition, in the related art, since the brightness of the backlight is kept constant or constantly varied, a lifelike image may not be displayed.